Transparency and colourlessness

As might be expected from a consideration of the factors discussed in Section 4.2, the imidisation process will stiffen the polymer chain and hence enhance Tg and thus softening points. Hence Vicat softening points (by Procedure B) may be as high as 175°C. The modulus of elasticity is also about 50% greater than that of PMMa at 4300 MPa, whilst with carbon fibre reinforcement this rises to 25 000 MPa. The polymer is clear (90% transparent) and colourless. 

Phosphorus trichloride twice redistilled was mixed very slowly with specially purified water, the flat porcelain dish in which the addition was made being floated on cold water during the operation. It was found that, if the addition was made too rapidly, a discoloration was produced, which at the end of the preparation was seen to be due to a fine powder suspended in the liquid. The phosphorous acid was then heated until it gave no precipitate with silver nitrate. It was then oxidized by cautious addition of dil. nitric acid, when an active effervescence ensued. Nitric acid was eventually added in slight excess, and the evaporation continued until all the nitric acid was expelled. The phosphoric acid thus prepared was transparent and colourless. The 100 per cent, acid did not affect litmus paper, and had no action on sodium carbonate. 

It is a transparent and colourless gas, which has no action on glass at ordinary temperatures. The formula has been established by analysis and from the vapour density. The compound is decomposed by heat, giving sulphur and fluorides of phosphorus, thus —... 

Fuorine reacts with graphite at 420-460° to give a solid varying in composition from CFjj.gg to CFg.ggg. When low in fluorine the substance is grey but, as the composition approaches C F, the solid becomes transparent and colourless. Its electrical conductance is very much less than that of graphite itself and it is chemically unreactive, not being attacked by concentrated acids or alkalis. The structure consists of a succession of puckered layers of carbon atoms with fluorine atoms attached to them so that the end-on view appears thus ... 

Hydrobromic acid is a gas, transparent and colourless, fuming strongly when mixed with the air. Its Sp. G. is 2 73. It is, in smell, taste, absorbability by water, and indeed all its properties, hardly distinguishable from hydrochloric acid but chlorine decomposes it, setting free bromine. The strongest solution of the acid is a fuming liquid of Sp. G. 1 29. 

It is a transparent and colourless gas, with a rather pungent, subacid smell, and a slight acidulous taste. Its sp. g. is l fl27 and it is so much heavier than air, that it may be collected in... 

Olefiant gas is transparent and colourless. When brought in contact with a flame in the air, it takes fire, and bums with a very luminous white flame. Mixed with its volume of chlorine, the two gases rapidly disappear, producing an ethereal or oily liquid, C H,C1, hence the name. But if mixed with 2 vols. of chlorine, and set fire to, the mixture bums off with a red flame, and an immense quantity of smoke, which is carbon deposited in the solid form, the hydrogen uniting with the chlorine. C. H,-fCl,=2HCH-C... 

This is a very abundant mineral, occurring chiefly in veins along with lead ore, heavy spar, and quartz. It is well known as fluor, or Derbyshire spar, and crystallises beautifully in cubes, octahedrons, and tetrahedrons, which are transparent and colourless, or purple, green, brown, or yellow. It also occurs in a massive semicrystalline form, capable of being cut and... 

The following researches originated in a consideration of the very remarkable phenomenon discovered by Sir John Herschel In a solution of sulphate of quinine, and described by him in two papers printed in the Philosophical Transactions for 1845, entitled On a Case of Superficial Colour presented by a Homogeneous Liquid internally colourless, and On the Epipolic Dispersion of Light. The solution of quinine, though it appears to be perfectly transparent and colourless, like... 

Styrene-a-methylstyrene copolymers, on the other hand, are marketed for extrusion and injection moulding. Compared to polystyrene, these copolymers have the advantage of higher softening points (104—106°C) they are also transparent and colourless. 

Forensic microanalysis by FTIR comprises the characterisation of dyestuffs on wool fibres [414, 482], and the examination of household and vehicle paint fragments [158,483,484]. High quality IR spectra can be obtained in transmission from individual paint layers by using thin sections and FTIR microscopy. /xFTIR may also be used to examine ink on various substrates, and to examine thin, transparent and colourless coatings. Forensics has driven development of /xFTIR. 

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